Selective hydrodeoxygenation of Dongming lignite ethanolysis-derived O-rich oil to fatty alcohols over a Ni-based LaMgAlOx

The directional upgrading from lignite liquefied crude oils to value-added oxygenated chemicals is an important pathway to optimize the clean non-fuel conversion system of lignite. However, O-containing group diversities and substituent differences make it difficult for such crude oils to be converted to fatty alcohols by simple hydrogenation. In view of this, a two-step cascade extraction system using the ternary mixed solution (petroleum ether/carbon disulfide, methanol, and water) was designed in this paper, and used for rapid enrichment of O-containing portions in Dongming lignite ethanolysis-derived crude oil to obtain O-rich oil (SP_E). In addition, a Ni-based LaMgAlO_x composite solid base, Ni@La₃₀BMO, modified by doping La was also prepared and used for the directional upgrading of SP_E to fatty alcohols, especially alkyl cyclanols. The results show that Ni@La₃₀BMO has excellent aromatic ring hydrogenation, >C-O- bridged bond cleavage, and >C_alOH retention properties, which are attributed to the texture property improvement of La₃₀BMO by doping La and strong Ni-La₃₀BMO interaction. Benzyloxybenzene can be selectively converted to cyclohexanol and methylcyclohexane over Ni@La₃₀BMO. >C_alOH retention is related to the synergistic transfer of H···H and ^δ+H···H^δ- after H₂ activation and the inhibition of H· and H⁺ transfer over basic sites modified by La. In addition, the total proportion of O-containing species in SP_E obtained by rapid enrichment is 81.3 %, and arenols (65.1 %) are dominant. After selective hydrofining, the proportion of fatty alcohols in refined oil (CHSP_E) increased significantly from 4.1 % to 79.0 %, and that of alkyl cyclanols reached 74.8 %. Overall, Ni@La₃₀BMO is a potential catalyst for the conversion of complex lignite-based crude oils into fine oxygenated chemicals of fatty alcohols, especially alkyl cyclanols. The step-wise directional conversion from complex derived crude oils to simple enriched oils and/or refined oils is a new idea worth considering.